I'm talking about the rear port on the vac. advance, and actually, both ports are for advance; contrary to popular belief, there is no retard control on this Toyota distributor. I struggled for years trying to get this sorted for a Weber install <img src="/forums/images/graemlins/smile.gif" alt="" /> Once I learned more about the ignition timing, things started falling into place.

I need to work on a Weber writeup to complement your Toyota carb documentation; good stuff you've compiled there.



lower diagram illustrates the different vacuum signals for each port on the distributor.

ported vacuum = any port on the carb above the throttle plates
manifold vacuum = anything port below the throttle plates